Gamma correction is a type of pre-distortion correction made to images or video frames to offset the non-linear behavior of display systems, such as cathode ray tube (CRT) displays. A characteristic of CRT displays is that the intensity they generate is not a linear function of the input voltage. Instead, the intensity is proportional to a power of the signal amplitude, also referred to as gamma. Gamma is usually greater than 1 and therefore the displays have a lower gain at low intensities and progressively larger gain at higher intensities. The Gamma Corrector IP core multiplies the input signal with the inverse of the display transfer function which results in a linear intensity response with respect to the original input signal.
Several gamma correction methods and values are used in television and display systems. Plasma, LCOS (Liquid Crystal on Silicon) and DLP (Digital Light Processing) displays have transfer characteristics that are different from that of CRT displays. Sometimes the display itself can have linear characteristics, but a gamma transformation (usually called degamma) may be required because of an earlier gamma correction made to the incoming signal.
The Gamma Corrector IP core is a widely parameterizable, multi-color plane gamma correction system. It can support almost any custom gamma correction requirement.
- Configurable number of color planes: 1 to 3
- Configurable number of bits per color plane: 4 to 12
- Option to specify gamma correction characteristics as an equation using a gamma value or by the actual mapping values of the look-up table
- Gamma correction look-up table can be run-time programmable
- Optimized gamma look-up table memory when same gamma correction is used for multiple color planes
- Gamma correction enable/disable control
- Option for sequential or parallel architecture for area or throughput trade-off
- Registered input option for input set-up time improvement
Block Diagram of the Gamma Corrector IP Core